Tuning device



July 24, 1928. 1,678,535

D. E. ROCKENFELDER TUNING DEVICE Filed March 23, 1925 2 Sheets-Sheet 1Den g1 E. Buckeye/o'er:

July 24, 1928. 1,678,535

D. E. ROCKENFELDER TUNING DEVICE Filed March 23, 1925 2 sums-sheet- 2 IF I HI I J l l l l l llhm IE- AL I MW Dewey E. Eockrye/or Patented July24, 1928.

UNITED STATES DEWEY EUGENE ROCKENFELDER, OF MONTPELIER, OHIO.

'r NI'NG DEVICE.

Application filed March 23, 1925. Serial No. 17,714.

The present invention consists of improvements in radio receiving setsthe principal object of which is to equip the set with a novel form oftuner which will greatly augment the selectiveness of the set and permlttuning in on a greater number of stations with more accuracy.

Other objects and advantages of the 1nvention will be apparent andsuggest themselves as the description of the accompanying drawingsproceeds.

While the drawings illustrate an embod1- ment of the invention it is tobe understood that I do not intend to limit myself to the exact detailshown and described, that various changes in the form, proportion andminor details of construction as would occur to a person skilled in theart may be resorted to without departing from the nature of theinvention or the claims hereto appended.

Referring tothe accompanying drawings forming a part of the inventionFig. 1 is a front elevational view of a radio receiving set constructedin accordance with the present invention;

Fi 2 is a top "plan view of the same showlng the top of the radiocabinet re: moved and the tube removed from its socket;

Fig. 3 is a transverse sectional view of a radio receiving setconstructed in accordance with this invention, the circuit wires beingshown fragmentarily; 1

Fig. 4 is a detail fragmentary perspective view of one of the tuningcylinders an drums or bores showing a part of the lever by which thedrum or core is operated;

Fig. 5 is a side elevational view of the condenser per se;

Fig. 6 is a sectional view of the condenser taken on line 6-6 of Fig. 5;and

Fig. 7 is a diagrammatical view of a radio receiving set constructed inaccordance with this invention. y

In the drawings, the cabinet of the radio receiving set is generallydesignated 8 and includes a base 9 having the box portion 10 of thecabinet superimposed thereon. The

front end of the base projects appreciably.

beyond the front of the box portion of the cabinet and is provided withtransversely extending channels 11 each of which merges into, at thefront "of the cabinet box, a shallower channel 12. The box portion ofthe ration. Moreover, a tube socket 15 of stand-- ard construction ismounted on the base 9. A grid leak and condenser 16, of a constructionhereinafter described, are also mounted on the base in proximity to thetube 15.

Of especial importance in the present invention is a tuning mechanismconsisting especially of a pair of dielectric elements 17 which, in thepresent instance, are shown to be of cylindrical configuration and aremounted transversely in the cabinet 10 with the terminals thereof insnug engagement with the inner faces of the front and rear walls of thecabinet. Each cylinder has wound around a portion of its periphery, aninsulated wire 18, the'convolutions of which are contiguous. It is, ofcourse, to be understood that any kind of wire desired may be employedfor this purpose, but it has been found that what is known in the art as#22 D. S. C. wire is especially adapted to function in accordance withthe teachlng of the present invention. This wire is tapped atpredetermined intervals, as indicated at 19, the wires extending fromthe points at which they are tapped to binding posts 20 mounted on thefront panel of the radio cabinet and equipped with contact 1 points onthe outer face of the panel which are adapted to be impinged against bydial hands 21 operable through the medium of knobs 22. The outercylinder and its wind= 'ing, designated P, constitutes the primary coiland the inner cylinder and its winding, designated S, constitutes thesecondary. or regenerative coil.

Slidably mounted in each of the cylinders 17 is a drum or. ,c ore 23which is preferably made ofmetal and is equipped at its forward end withany extension providing an annulus 24 which is engaged by the reducedright angled inner end 25 of a lever 26, the outer end of the leverbeing detachably engaged by a knob 27 which is superimposed on anindicating finger 28 and secures the latter from displacement. It willbe noted,

upon reference to Fig. 3 of the drawings,

, the calibrations. As shown in Fig. 4 of the drawings each of thecylinders 17 is provided with a longitudinally extending slot 30 throughwhich the right angled end of the lever 26 is movable.

The grid leak and condenser, as shown in Figs. 2, 5 and 6, consists of acondenser base 31 upon which a pair of copper plates'33 are mountedwhich have a mica or other insulating sheet 34 interposed therebetween.The grid leak base 36 is mounted directly on top it of the uppermostcopper plate. In order that the copper plates and mica sheet may be heldin snug engagement, four (4) wood screws extend downward through gridleak base 36 and into condenser base 31. The copper plates areelectrically connected by screw posts 35 which latter extend upwardlythrough a grid leak base 36 and also through carbonized ends 37 of aninsulated strip 38 which may be made of zolenite or other suitableinsulating material. The carbonized ends 37 of the strip 38 areconnected by a carbon thread 39. As shown to advantage. in Fig. 6, thegrid leak base 36 is detachably mounted on the condenser base 31.Moreover, the condenser elements 33 and 34 are secured to the lower faceof the grid. leak base 36 by suitable adjustable means 40 mounted onposts 35.

As [diagrammatically illustrated in Fig.

7 of the drawings, the circuit includes A batteries 41 and B batteries42 connected to tube 43 and rheostat 44, through wires 45 and 46respectively. An aerial 47 is in connection with the grid leak condenserand tube 43 through the medium of the wire 48 and in connection with theoscillation transformer through medium of wire 49. The oscillationtransformer, in the present instance, consists of the primary andsecondary coils, the former of which leads to a ground through wire 50.The B batteries 42 are connected to the head phones and secondarywinding by wires 51.

In use of the radio receiving set constructed in accordance with'thepresent, invention, the knobs 22 are operated in a manner well known inthe art in order to tap in on the coils P and S. The drums or cores 23are urged into the cylinders of the coils by manipulation of the knobs27 in an apparent manner so as to bring them into a position concentricto the convolutions of wire 18.

The inductance of the coils is varied by the drums or cores 23 throughthe dielectric cylinders 17. Consequently, by advancing the drums intoand retracting the same from the portion of the cylinders, around whichthe wire 18 is convoluted, a variable induction is obtained in boththeprimary and secondary circuits and as a result very fine tuning isaccomplished. The tapped primary and secondary keep the tube coilsbalanced and permit a coarse change of wave length in an apparentmanner. Consequently, the variance in the induction is accomplished bymovement of the drums or cores 23through the medium of the knobs 27,independent of any hook-up circuit. The position of the drums isdetermined by the relative positions of the fingers 28 on thecalibrations of the plates 29.

It is, of course, to be understood that the device is susceptible ofnumerous changes, within the scope of the claims hereto appended, toadapt the device for use under different conditions. I It has been foundpractical, however, to adopt the present hook-up and use the same inconjunction with the tuner above described and also the particular typeof condenser and grid leak herein employed which latter provides apositive contact between the copper plates and posts upon which they aresecured. The grid leak may be varied by a change inthe carbon thread 39.

What is claimed is 1. A tuning device for radio circuits, comprising aprimary winding and a secondary winding arranged in inductive relation,a pair of metallic elements disposed one in operative relation to eachwinding, each of said metallic elements being equipped at one end withan annulus, the latter having an aperture therein, levers for moving themetallic elements, one end of each of which is bent at right angles andengaged in the aperture of one of the annuli, said levers beingindependently operable to selectively move said metallic elements, andmeans for varying the inductance of each winding.

2. A tuning device for radio circuits, comprising a pair of inductancecoils arranged in inductive relation with their axes substantiallyparallel to each other, a metallic element disposed within the field ofeach coil, each metallic element bein equipped at one end with anannulus, an means connected to each annulus for moving each elementindependently of the other with respect to said'coils.

3. A tuning device for radio circuits. comprising dielectric cylindersarranged side by side, a winding on each cylinder, a metallic elementdisposed within each cylinder, each of said metallic elements beingequipped at one end with an annulus, levers for movin the metallicelements connected to the annuli for varying each of said metallicelements cylinders being equipped at one end with an with respect tosaid dielectric cylinders and annulus, levers connected to each of thean- 10 v windings. 1 nuli for moving the metallic cylinders longi- 4. Atuning device for radio circuits, comtudinally of its dielectriccylinder, and prising a pair of dielectric cylinders armeans for varyingthe inductance of said ranged side by side, a winding on eachcylwindings. inder, av metallic cylinder disposed within In testimonywhereof I aflix my seal. each dielectric cylinder, each of said metallicDEWEY EUGENE ROCKENFELDER-

